I have a wine cellar that is Not attached to the house. I am looking to increase the height of this space by 300mm (about 12 inches). Raising the ceiling is not an option, but Iím hoping lowering the concrete floor is. Is this an option and if so, what would be involved? Thanks.

I doubt this is something you could do without major renovation. If your flooring is going to be below ground you'll need a foundation; however, there may be ways around this. I've never heard of someone increasing the height of a room\area by digging deeper!

Leave the old concrete floor as a 2' or so wide border around the perimeter so the walls are supported, and jackhammer the center of the floor.
Then you'll need false walls to keep people from falling off this 12" step.

I think leaving a boarder to support the walls is the way to go, but 2 foot (that is what you mean, right?) is pretty big. Most of the floor space would be the boarder. the room is 2m x 3m x 1.9m high.

I think leaving a boarder to support the walls is the way to go, but 2 foot (that is what you mean, right?) is pretty big. Most of the floor space would be the boarder. the room is 2m x 3m x 1.9m high.

I love the metric system!

Thanks for the advice.

G.

Depending on the soil strength and with a small 'footprint' like this you maybe could go with less border but those calculations are beyond me.

The metric system is superior. I've heard that a spacecraft crashed because somebody forgot to convert. Using inches and feet is a continuing hassle.